Modulus check
live demo

const sortcode = '822220';
const accountNumber = '00110022';
const apiKey = 'YOUR_API_KEY';

const url = `https://wsp.esortcode.com/uk/v1/validateaccount?key=${apiKey}&sortcode=${sortcode}&accountNumber=${accountNumber}`;

fetch(url)
  .then(response => response.json())
  .then(data => {
    console.log('Valid:', data.modulusCheck.valid);
    console.log('Bank:', data.branches[0].bankName);
  })
  .catch(error => console.error('Error:', error));

import requests

sortcode = '822220'
account_number = '00110022'
api_key = 'YOUR_API_KEY'

url = f'https://wsp.esortcode.com/uk/v1/validateaccount'
params = {
    'key': api_key,
    'sortcode': sortcode,
    'accountNumber': account_number
}

response = requests.get(url, params=params)
data = response.json()

print(f"Valid: {data['modulusCheck']['valid']}")
print(f"Bank: {data['branches'][0]['bankName']}")

<?php
$sortcode = '822220';
$accountNumber = '00110022';
$apiKey = 'YOUR_API_KEY';

$url = "https://wsp.esortcode.com/uk/v1/validateaccount?key=$apiKey&sortcode=$sortcode&accountNumber=$accountNumber";

$response = file_get_contents($url);
$data = json_decode($response, true);

echo "Valid: " . ($data['modulusCheck']['valid'] ? 'Yes' : 'No') . "\n";
echo "Bank: " . $data['branches'][0]['bankName'];
?>